In a related art, a hinge used on a window frame and a window sash can be designed in such a manner that a fixing rod and a rail are vertically aligned. Namely, when the hinge is in a closed state, a first centerline of the fixing rod and a second centerline of the rail are mutually overlapped. Through such structural design, processing of the hinge is convenient to control, since materials of the window frame and the window sash in the related art are mostly formed by extrusion of aluminum alloy (the extrusion is a plastic processing method for applying strong pressure on metal blanks placed in a mold cavity (or an extrusion cylinder) to force the metal blanks to produce directional plastic deformation for extruding the metal blanks from mold holes of an extrusion mold to obtain a part or semi-finished product having required section shape and size and certain mechanical property). According to a design standard for door notch and window notch, to reduce an installation error between the window sash and the window frame, a width of the notch in the window frame is different from a width of the notch in the window sash, a side of the notch in a window frame is aligned with a side of the notch in a window sash, and a centerline of the notch in a window frame and a centerline of the notch in a window sash are not in line. When a first centerline of the fixing rod and a second centerline of the fixing rod installation groove in the hinge are not in line, installation precision between the window frame and the window sash may be influenced.